Side mirrors are angled to reduce blind spots, but they can't eliminate them entirely — there's almost always a zone just behind and to the side of the vehicle where another car, cyclist or motorcycle can sit invisibly. This is exactly why K53 training insists on a shoulder check (a quick glance over your shoulder) before changing lanes, not just a mirror check. Skipping the shoulder check is one of the most common reasons learners lose marks on the practical test, and it's also a genuine cause of real-world lane-change collisions. The habit only takes a second once it's built in, but it has to become automatic — checking mirrors, then blind spot, then signalling, then moving.
Source: K53 Defensive Driving Manual
Frequently Asked Questions
Why isn't a mirror check enough before changing lanes?
Mirrors have a fixed field of view and can't show the zone directly beside and slightly behind your vehicle, where a car or motorcycle can sit completely hidden.
When exactly should I do a shoulder check?
Just before you start moving into the new lane, after you've already checked your mirrors and signalled — it should be the last check before you commit to the manoeuvre.
Do motorcycles have bigger blind-spot risks?
Motorcycles are smaller and easier to lose in a car's blind spot, which is one reason riders are advised to avoid lingering in other vehicles' blind spots.
Is skipping the shoulder check a common test mistake?
Yes, it's one of the most frequently penalised observation errors in the K53 practical test, even among learners who otherwise drive well.